59 lines
1.6 KiB
C++
59 lines
1.6 KiB
C++
/*!
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@file
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Forward declares `boost::hana::repeat`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_FWD_REPEAT_HPP
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#define BOOST_HANA_FWD_REPEAT_HPP
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/when.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! Invokes a nullary function `n` times.
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//! @ingroup group-IntegralConstant
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//!
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//! Given an `IntegralConstant` `n` and a nullary function `f`,
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//! `repeat(n, f)` will call `f` `n` times. In particular, any
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//! decent compiler should expand `repeat(n, f)` to
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//! @code
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//! f(); f(); ... f(); // n times total
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//! @endcode
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//!
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//!
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//! @param n
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//! An `IntegralConstant` holding a non-negative value representing
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//! the number of times `f` should be repeatedly invoked.
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//!
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//! @param f
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//! A function to repeatedly invoke `n` times. `f` is allowed to have
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//! side effects.
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//!
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//!
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//! Example
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//! -------
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//! @include example/repeat.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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constexpr auto repeat = [](auto const& n, auto&& f) -> void {
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f(); f(); ... f(); // n times total
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};
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#else
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template <typename N, typename = void>
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struct repeat_impl : repeat_impl<N, when<true>> { };
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struct repeat_t {
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template <typename N, typename F>
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constexpr void operator()(N const& n, F&& f) const;
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};
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constexpr repeat_t repeat{};
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#endif
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_FWD_REPEAT_HPP
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